Aim of this phase 1b study is to evaluate safety and preliminary efficacy of stereotactic body radiation therapy in patients with metastatic renal cell carcinoma treated with VEGFR, mTOR or immune checkpoint inhibitors.

This is prospective phase 1b study.

Patients with metastatic RCC receiving targeted or IO therapy (VEGFR inhibitor or mTOR inhibitor or checkpoint inhibitors in approved treatment lines and in standard therapeutic regimens) with stable diseaseor durable partial response for at least 4 months, are enrolled in the study.

The initial examination includes CT with contrast, where the selected measured 2 metastatic sites, stable for at least 4 months but no more than 6 months of targeted therapy (increase or decrease in size in the course of targeted therapy should not exceed 10%). Metastases have to be located in one organ. Allowed location of metastases: lungs, liver, lymph nodes, contralateral kidney, adrenal gland.

Size of selected metastases should not be less than 5 mm and not more than 4 cm.

Inclusion Criteria:

1. clear cell renal cell carcinoma
2. confirmed distant metastases
3. previous nephrectomy
4. stable disease or durable partial response on recommended targeted and IO therapy
5. age: > 18 years
6. signed informed consent

Exclusion Criteria:

1. unability to select first and second metastases
2. history of serious cardiac arrhythmia, congestive heart failure, angina pectoris, or other severe cardiovascular disease (i.e., New York Heart Association class III or IV)
3. other malignancy
4. grade 3 and 4 toxicity of targeted therapy